When sheets of plastic material, particularly film/foam laminates having at least one outer film layer, are used for covering materials, such as swimming pool covers, there is often a need for the sheets to be joined together to provide a large area. Problems have been encountered in joining sheets including plastic foam material to provide a strong, waterproof hinged joint, without damaging the outer layer of the cover. Another unsolved problem relates to joining sheets of foam plastic materials for use as covering for garden beds.
Glass, U.S. Pat. No. 3,442,415, shows a plastic hinge element having an adhesive surface which is adhered to a rigid foam container forming a hinge. The hinge is not disclosed as containing a foam layer. The patent to Lewallen, U.S. Pat. No. 3,445,052, describes a plastic hinge for joining a laminate in which the outer layers of the laminate, which may be plastic film, are stripped away leaving a section of exposed inner ply or plies, which may be plastic foam. The laminate is hinged after removal of the outer skins.
The patent to Kruger, U.S. Pat. No. 4,563,379, discloses a sealing web covering a joint between two webs of plastic for use in a roofing application. The two webs are joined by heating or solvent web welding a thinner cover tape to the two webs. Plastic films are not disclosed. Alfter, U.S. Pat. No. 3,962,016, shows a process for joining abutting thermoplastic synthetic resin foam sheets by heating a metal strip to above the softening point of the foam webs and applying pressure. Hewitt, U.S. Pat. No. 3,468,732, discloses a method of butt joining thermoplastic sheet material by spin welding by application of a series of thermoplastic buttons between the abutting edges to be joined. The patent to Long, et al., U.S. Pat. No. 3,388,134, shows a method of sealing two abutting seamed sheets of rubber foam material by removing a strip of the covering layer adjacent the seam and adhering a thinner, sealing strip of foam along the prepared strip, forming a foam/foam seal using adhesive material to join the layers. Strauss, U.S. Pat. No. 3,445,315, shows a method of sealing two abutting film or plastic sheets by solvent welding a capping strip across the abutted edges. Kuntz, U.S. Pat. No. 3,301,732, shows a method for joining two rigid honeycombed panels by bonding a glass-fiber containing strip along the joint between the abutted sheets.